The response of N and P efficiency in forage maize to different urea and broiler litter levels under short-term drought stress conditions

Water and nutrient availability are two major constraints to forage maize production in arid and semi-arid areas; however, the effect of different N levels from organic and inorganic sources on nutrient (i.e., N and P) efficiency under drought stress conditions is not well known for maize faming. Thus, a field study was conducted with the objective of determining the effect of N fertilization and drought stress on N and P efficiencies in maize (cv. SC 704) crop. The experimental setting consisted of four rates of N application (0, 100, 200 and 300 kg.ha−1 N) as urea and broiler litter and two irrigation regimes (full irrigation and irrigation stop at tasseling stage lasted only for two weeks) that carried out at the Research Station of Agricultural Faculty, Shahrekord, Iran, during 2008-2009. Results indicated that no significant difference in N and P efficiencies between the two irrigation regimes. Although the effects of fertilizer treatments on N agronomic efficiency, N physiological efficiency, P agronomic efficiency and aboveground dry matter were significant, but N and P recovery efficiencies and P physiological efficiency were not significantly affected by N treatments. The highest aboveground dry matter (32289 kg ha-1) and N agronomic efficiency (62.7 kg.kg-1) were observed with 300 kg.ha-1 N from broiler litter, but this efficiency did not differ from all urea N levels. The application of 100 kg.ha-1 N from broiler litter resulted in the greatest N and P physiological efficiencies (141 and 114 kg.kg-1, respectively) and these efficiencies were significantly different from all urea N levels. It is concluded that broiler litter application have had higher N agronomic and physiological efficiencies than urea application, and that short-term drought stress at tasseling stage apparently does not have an influence on the response of nutrient efficiencies to different N rates and sources.